What happened
On September 15, 2001, a TAM Linhas Aéreas Fokker 100, registration PT-MRN, was operating a scheduled passenger flight from Recife to Campinas. While cruising approximately 70 NM from Belo Horizonte, the aircraft experienced an uncontained failure of the right Rolls-Royce TAY 650-15 engine. The failure caused the fan disk and the first three stages of the low-pressure compressor to separate from the engine and be projected forward and toward the left side of the aircraft.
This event resulted in an explosive decompression of the fuselage. Debris from the engine penetrated the airframe, specifically striking the area near window 19. The impact of a stator vane disk fragment into the cabin caused the fatal injury of one passenger. The crew initiated an emergency descent and diverted to Confins Airport in Belo and Horizonte. Despite the severe damage to the engine and fuselage, the crew successfully landed the aircraft at 20:42 local time. An emergency evacuation was performed, during which three passengers sustained minor injuries.
The investigation
The CENIPA investigation focused on the mechanical failure of the engine and the subsequent structural damage. Investigators examined the wreckage of the engine and found that several components, including the fan disk and compressor stages, were missing. While the fan disk itself was not recovered due to the difficult terrain in the Diamantina region, laboratory analysis of recovered blade fragments revealed evidence of fatigue.
Technical analysis of the flight data recorder (DFDR) showed that the right engine parameters dropped to zero immediately following the failure. The investigation also reviewed maintenance records, which indicated that all inspections and services were up to date. Investigators also examined the use of reverse thrust settings, noting that the operator had been using the "emergency maximum reverse thrust" position during routine operations at Santos Dumânt Airport to handle shorter runway lengths, a practice that was permitted by local regulations at the time.
Findings
- The primary cause of the accident was an uncontained engine failure resulting from fatigue in the fan blades, likely induced by engine flutter.
- The separation of the fan disk and compressor stages caused the structural penetration of the fuselage and the subsequent explosive decompression.
- The engine failure led to the death of one passenger due to blunt force trauma from engine debris.
- There was a possibility that previous routine use of the engine's reverse thrust in a specific N1 power range (between 57% and 75%) may have contributed to the development of fatigue cracks, although the specific engine power settings during the accident flight did not meet the threshold for immediate crack propagation.
Safety action
- The aircraft manufacturer was requested to investigate the feasibility of design modifications to prevent engine operation within the critical N1 range and to implement an alert system for the crew.
- An Emergency Airworthiness Directive was issued to restrict the use of reverse thrust in the critical 57% to 75% N1 range to emergency situations only and to mandate ultrasonic inspections of the blades.